In order to facilitate the transition from conventional analog television systems to digital television systems, current television receivers are capable of receiving and processing both analog television signals, e.g., National Television Standard Committee (NTSC) television signals, and digital television signals, e.g., high definition television (HDTV) signals. FIG. 1 depicts a high level block diagram of a tuner portion 100 of such a television receiver. An exemplary television receiver is disclosed in U.S. patent application Ser. No. 09/140,257, filed Aug. 26, 1998, which is herein incorporated by reference.
The tuner portion 100 comprises an antenna 102, a radio frequency (RF) tuner 104, an intermediate frequency (IF) module 106 and an automatic gain control (AGC) circuit 108. A RF modulated input television signal is received at the antenna 102 or other input terminal such as a cable television set top box, satellite television set top box and the like. The input television signal may comprise either an analog NTSC television signal or a digital HDTV television signal. The RF tuner 104 tunes the input television signal for a particular channel and down converts the input television signal to an IF television signal. The IF tuner 106 converts the IF television signal into a downstream, baseband television signal. The AGC circuit 108 receives the baseband television signal and derives an AGC control signal coupled to an amplifier in the RF tuner 104. The gain of the RF tuner 104 is adjusted in response to the AGC control signal.
However, the transition from analog television systems to digital television systems requires using additional bandwidth in the existing terrestrial television spectrum. Each television broadcast station is allocated an additional broadcast channel to transmit the HDTV television signal or multiple standard definition digital signals. This channel requires usage of additional bandwidth over the currently allocated bandwidth utilized to transmit analog NTSC television signals. With these additional channels, the broadcast television signal is more susceptible to cross-modulation and inter-modulation distortion. As such, the television receiver must improve its linearity performance in view of distortion associated with the input television signal.
Therefore, a need exists in the art to improve the reception of television signals.